Photophobia in a blind patient: an alternate visual pathway

Abstract

Photophobia is a common neurological and ophthalmological symptom that has been associated with a growing number of neurosurgical conditions, especially compressive lesions. The exact signaling pathways and neurophysiological features of the disorder are not well understood; however, data from multiple studies have shown the significance of the trigeminal system and the pretectal nuclei in its pathophysiology. The authors report on a rare case of a blind patient who presented with photophobia without evidence of light perception. They also review the literature and early experimental data in an effort to understand the possible neuronal pathways and structures involved in photophobia.

Autologous Serum Tears for Treatment of Photoallodynia in Patients with Corneal Neuropathy: Efficacy and Evaluation with In Vivo Confocal Microscopy

“…Photosensitive retinal cells may contribute in part to light aversion. 64 Presence of photophobia in blind patients 65 and after optic nerve resection in rats 66 demonstrates that an intact optic nerve is not essential for sensitivity to light. Such photosensitive non-image forming cells have been directly implicated in photophobia in migraine, during which light increases the pain.…”

Photophobia as the Visual Manifestation of Chiasmal Compression by Unruptured Anterior Communicating Artery Aneurysm -Case Report-

“…The causative mechanism is thought to involve the trigeminal pathway with possible input from the pretectal nuclei, occipital lobe, and thalamus. 1,6,12,18,21) Interestingly, photophobia may have been caused by chiasmal compression in a small number of patients. Photophobia was observed in one patient with a hypophyseal tumor, and in another patient with recurrent craniopharyngioma.…”

“…The mechanism causing light intolerance associated with corneal disruption, iritis, meningitis, 11) and migraines remains unclear, and is presumably related to irritation of the trigeminal afferent pathway. 1,6,12,18,21) Anterior segmental disease of the eye, subarachnoid hemorrhage, 3,8,14,22) unruptured cavernous carotid artery aneurysm, 7) and retrochiasmal demyelination 9) are all well known causes of photophobia. A small number of reported cases have suggested that photophobia is a rare symptom of chiasmal compression.…”

Blurring the Boundaries of Vision: Novel Functions of Intrinsically Photosensitive Retinal Ganglion Cells

“…By contrast, ipRGCs are not required in a mouse model of nitroglycerin- induced migraine 99. Other studies, however, have identified visually blind (lacking rod and cone photoreceptors) people that still experience photoallodynia, strongly suggesting that ipRGCs mediate this function in both migraine and non-migraine conditions 95,100. Furthermore, supporting evidence from rodents shows that light directly or indirectly modulates migraine-related chemo- and mechano-sensitive dura neurons, which terminate in close apposition to ipRGC projections in a thalamic region mediating pain 95.…”